Reinforcement for concrete



Feb. zo, 1940'. L, HERZKA 2,191,233

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fom/D MZK/4 ATTORNEY,

20' tant from the axis.

Patented Feb. 20, 1940 UNITED STATES a 2,191,233 i REINFonoEMENT Fon CONCRETE Leopold Herzka, Vienna, Germany, assigner, by mesne assignments, to Comtec Limited.:London,A

England Application December 20, 1938, Serial? Na-16,819 In` Austria DecemberrZl, 1937 .i claims. (o1. 724-111) The present invention relates` to reinforcements for concrete consisting of bars.

For` producing reinforced concrete, steels.` are` at present used, the mechanical `properties of which are improved by cold stretching. The

best known among these types are those in which two round vbars are twisted together and those which consist only of lone round` bar twistedl round its axis. rst type when embeddedv in concrete have a considerable adhesion force, but` on the other hand the improvement of the mechanical properti'es in comparison with the untwisted bars of vthe same material is only slight in view 4of the 1:5` unequal stresses in respect to the axis towhich the steel libres aresubjectin twisting. The bars of the second type show high mechanical properties owing to their circular cross section and` tothe uniform stretching` of the libres: equidis- On the other `hand their adhesion force in concrete issmall owing to their circular cross section. It has been tried to` eliminate the latter drawbackv by providing the steel with ribs forming spirals in consequence of the 2li` twisting. This however results in a reduction ofV the mechanical strength" as the fibres situated in the ribs are exposed to different and higher `strains than the fibres of the round bars.

The main object of the invention is a reinet).` forcement for concrete uniting the advantages ci" the two steel reinforcements mentionedzabove without their drawbacks. l

It is a further object of the. present invention y to provide a composite reinforcement consisting` 35 of two or more bars, said bars having faces being in intimate contact throughout, said bars being twisted together in helical relationship. It is still another object of the invention to make the bars with faces having a rectilinear cross sec- 40. tion being in intimate contact throughout. In order to improve the mechanical strength of the composite reinforcement it may be of advantage to give the contacting faces a cross seci,

tion in form of a broken or wavy line.

45 It is still a further object of the invention to improve the adhesion force of the composite reinforcement by making one of the bars forming the `reinforcement protruding, preferably in radial direction, beyond the other bar or bars, 50 and twisting said bars together in helical relationship forming hereby a helical ridge or roll along the reinforcement. The adhesion force of the reinforcement may also be improved by providing at least along one edge between the 55 contacting faces of the bars and the substantially Itis true that the bars ofthe cylindrical circumferential` faces. of said bars` `further narrower faces inclined.` towardssaid contacting faces forming` thereby a groove or. grooves alongthe outer surfaceof saidrelnforcement.

Accordingl to a. preferred` embodiment `of the invention` the reinforcement may` be produced` by twisting. two commercial` half round. bars, having their plane faces being inintimate contact. throughout, around. their common axisof 10 gravity. By` using" two. half round bars the. reinforcement` has substantially the` form of one` round bar;` in this case the elongation of the libres` is` practically equal to. their elongation, in;

a twisted round bar. however an excellent adhe- 154 sion in the `concrete is obtained by the helical faces even` if these faces are in perfect correspondence, as the edges of the bars form a profnounced seam along the surface of the rein-` forcement which resembles in: its appearance to thatzcf, a round bar. The adhesion of this sealfn` may be increased by having the one4 helical face. protruding beyond` the` other whereby a helical ridge` on roll is formed alongthe reinforcement the outer cross-section of which section comes. near to vthat of a round bar. As this ridge or roll is formedof a bar. uniformly stressed on its cir.- cumference, no detrimental elongationsl can occur. The adhesion force. of the `twisted reinforcing barsmay` berincreased by the helical face 3o of each` bar being flushwith theremaining outer surface of said bar or forming` an angle` with same. Thereby a helical groove is `formed. running round the twistedreinforcement.

In the accompanying drawing which illustrates several embodiments of the invention,

Figure 1 shows a perspectivegview of a reinforcement` composed of two equal half round bars,

Figure 2 shows a perspective view of parts of 40 the barsshown in Figure 1, Figure 3 shows a cross section through a bar shown in Figuresv 1 and 2.

Figure 4 shows a cross section of a reinforcement made of equal half round bars displaced in respect to each other so that the one helical face protrudes beyond the other,

Figure 5 shows the cross section of a reinforcement made of unequal half round bars,

Figure 6 shows a cross section of a reinforce- 50 ment having outer faces with a rectilinear cross section adjacent to the contacting helical faces,

Figure 7 shows a cross section of a reinforcement with helical faces` forming angles with the Y other parts of the outer surface,

Figure 8 shows a cross section of a reinforcement with helical faces which passes flush with the other parts of theouter surface,

Figure 9 shows a cross-section of a reinforcement consisting of two bars being in intimate contact along two faces `with a cross section in form of a broken line,

Figure 10 shows the cross section of areinforcement consisting of two bars having faces with a cross section in form of a wavy line, and

Figure 11 shows a cross section of a reinforcement made of three bars.

The reinforcement according to Figs. 1,-3 `is composed of two half round bars 2, 2a of equal cross section placed uponeach other and` intimately contacting along a helical face whereby the .helical faces of the bars are in intimate con,- tact and perfect correspondence. The reinforcement is produced by placing upon eachy other commercial half round bars in such a manner, that the plain faces are made to contact whereupon'they are twistedtogether round the center line of the cross section, i. e., round the axis of the bars joined together. Owing to the irregularities inherent to the bars which are increased by twisting the edges 3 will not exactly touch each other but they will partly protrude beyond the substantially circular cross section formed by the circumference of the bars twisted together and will partly form a groove 4. These projectingparts and grooves will impart to the reiny forcement an excellent adhesion force which may 40^fwith the bars. The same effect may be obtained with bars of different cross sections as shown in Figure 5. `The barV 'I has a larger cross section then the bar Idr and protrudes on both sides with ports of its helical face adjacent tothe-edges 8 beyond the bar la. In this case too the twisting does not destroy the connection of the libres in the bars. Fig. 6 shows the cross section of l a reinforcement similar to the reinforcement shown in Fig. 5. In the reinforcement shown in Fig. 6 the faces Il] and Ia. adjacent to the helical faces I ofthe bars 9 and 9a. are plane prolongations of thehalf round faces forming the circumferential surface of the reinforcement.

These plane faces I0 and Illa are parallel to a plane passing through the axis of the reinforcement. v y n 'Ihe reinforcements shown in IFigs. 7 and 8 are provided with grooves. These grooves are formed ontheuouter surface of the reinforcement shown-in Fig. `7 by the inclined faces I4 connecting the helical faces lI and the half round faces I6 of the bars -I3 and I3a. On the outer surface of the reinforcement shown in Fig. 8 grooves are formed by arc shaped faces I4 passing flush into the helical faces and into the half round outer faces I'I of the bars I3.

In order to warrant a reliable guidance in twisting the bars it is advantageous to use contacting faces having a cross section in form of a broken line I8 as shown in Fig. 9 or in form of a wavy line I9 as shown in Fig. 10.

vIn order to produce more than two adhesive seams formed by edgesl of the bars it is useful to combine the reinforcement of three bars 20, 20a, and 20h, as shown in Fig. 11. In this case the section of the bars is that of a sector or of a segment of a circle.

Having thus described my invention, I claim:

1. Reinforcen'ientr for concrete consisting of bars. said bars having faces'being in intimate contact throughout, said bars being twisted together in helical relationship to provide a composite reinforcement.

2. Reinforcement for lconcrete consisting of bars, said bars having faces with a rectilinear crosszsection being in intimate contact throughout, said bars twisted together in helical rep lationship to provide a composite reinforcement.

3. Reinforcementfor concrete `consisting of bars, said bars having faces with a cross section in form of a broken line being in intimatecontact throughout, said bars being twisted together in helical relationship.

4. Reinforcement for concrete consistingy of bars, said bars having faces being in intimate contact throughout and the face of one of said bars protruding in radial direction beyond the other bar, saidibars being twisted together in helical rrelationship vto provide, a composite reinforcement. o

5. Reinforcement for concrete consisting of bars, said bars having faces with a rectilinear cross section in intimate contact throughout and the face of one of said bars being wider than the face or faces of the other bar or bars, said bars being twisted together in helical relationship to provide a composite reinforcement.

6. Reinforcement for concrete consisting of bars, said bars having faces being in intimate contact throughout andA having at least along one edge between said faces andthe substantially cylindrical circumferential faces of said Kev:

bars further narrowerfaces inclined towards said intimately contacting faces,` said bars being twisted together in. helical relationship to provide a composite reinforcement '7L Reinforcement for concrete consisting of bars, said bars having `faces being in intimate' contact throughout and having outer faces forming a substantially cylindrical outer surface, said bars being twisted together in helical relation-- ship to provide a composite reinforcement.

` LEOPOLD HERZKA. 

